If you are revising for an exam it can be a good idea to look at some past papers to see what type of questions you can expect. I chanced across an A-Level Physics paper while looking for information about the Mark V telescope at Jodrell Bank. It is from 2003 and is titled "Nuclear Instability: Astrophysics Option". I'm sure it was called "Astronomy and Optics" in my day but that was when the AQA was the NEAB.

It is good to find out what sort of things A-Level students are expected to know as I can then expect 1st year undergraduates to know them as well! So they should know about absolute and apparent magnitudes, half-lifes (not the game), resolution and sensitivity, the Balmer series....